Method of fabrication of cathode ray electrostatic printing or recording device



Sept. 8, 1964 R. s. HOWELL 3,147,534

METHOD OF FABRICATION 0F CATHODE RAY ELECTROSTATIC PRINTING OR RECORDING DEVICE Filed AugpSl, 1961 2 Sheets-Sheet 1 INVENTOR.

RICHARD s. HOWELI M kg AGENT Sept; 8'. 1964 R. s. HOWELL METHOD OF FABRICATION OF CATHODE RAY ELECTROSTATIC PRINTING 0R RECORDING DEVICE 2 Sheets-Sheet 2 INVENTOR.

RICHARD S. HOWELL Filed Aug. 31, 1961 3 8 a m mm 4 a V, v/ V L fr U 1.: I h I: {I ml .rg .IIIWIIIH l :12 11 I v A 2 w I I a M 8 2 M 5 4 W q a 4 w W ml 1 m 3 m 4 l I N I 1W 6 w v 3 w United States Patent "ce 3,147,534 METHOD OF FABRICATION 0F CATHODE RAY ELECTROSTATIC PRINTING 0R RECORDING DEVICE Richard S. Howell, King of Prussia, Pa., assignor to Burroughs Corporation, Detroit, Micin, a corporation of Michigan Fiied Aug. 31, 1961, Ser. No. 135,369 6 Claims. (Cl. 2925.17)

The invention hereinafter described and claimed has to do with cathode-ray devices, but more particularly to the method of fabricating an electrostatic printing or recording head for use in a cathode-ray tube. With still more particularity the invention relates to the method of fabricating a combined cathode-ray tube and electrostatic printing and recording head, whereby such printing or recording may be initiated by means of the cathode beam of the tube, in the manner described and claimed in the co-pending application of Robert E. Benn entitled Electron Tube Serial No. 131,337, filed August 14, 1961, and assigned to the assignee of the present invention, and as described and claimed in applicants co-pending application entitled Cathode Ray Electrostatic Printing or Recording Device, filed concurrently herewith.

The electrostatic recording process consists broadly of three steps. The first step comprises establishing, or printing, electrically charged areas on selected portions of the recording medium, which areas are representative of information. The second step consists of developing such charged areas on the recording medium, by making them visible, for example. The third step, which is optional, consists in fixing or rendering such developed areas substantially permanent. In electrostatic process these three steps take place sequentially and at physically separate locations.

. In the co-pending application Serial No. 729,847, filed April 21, 1958, entitled Electrographic Recording Process and Apparatus, by Robert E. Benn and Richard S. Sakuari, which application is assigned to the assignee of the present application, the advantages of positively initiating the establishment of a charged area on a recording medium by creating an electrical discharge between an initiating electrode and a print electrode are set forth. In that co-pending application a separate pulse generating source for each print electrode and each initiating electrode of a matrix print head is required. The simultaneous occurrence or application of print and initiating pulses to corresponding print and initiating electrodes initiate the establishment of a charged area on the recording medium located in. a gap between the print and initiating electrodes of the print head and a back electrode.

It is brought out in the above identified Benn et al. application Serial No. 729,847, that great simplification in the printing station, in the structure of the print heads, and the necessary control and pulse generating circuitry required to print alphanumeric information, for example, results when one type of the electrodes in the matrix print heads, the print electrodes, for example, are connected in parallel. Still greater simplification is possible if each row of parallel connected print electrodes is replaced by strip or bar electrode, as described and claimed in the co-pending application Serial No. 734,253, filed May 9, 1958, now Pat. No. 3,068,479 entitled Electrographic Recording Apparatus, by Robert E. Benn, Richard S. Howell, and Richard S. Sakuari which application is assigned to the assignee of the present invention.

The present invention has for its primary purpose to provide a method whereby the teaching in the above mentioned Benn, Howell, and Sakuari co-pending application may easily be incorporated in a cathode-ray tube as taught in the above identified co-pending Benn applica- 3,147,534 Patented Sept. 8, 1964 A particular advantage of a system as taught in theabove identified co-pending Benn, and Benn et al. applications is that it is only the initiating or selection electrodes which need to be driven by the cathode-beam of such a tube and since the occurrence of the discharge from an initiating electrode to the adjacent printing or bar electrode which is connected to a suitable printing voltage, automatically brings the two electrodes within a few hundred volt-s of each other in potential, the voltage excursion of the initiating electrodes as a result of a secondaryemission phenomena is restricted, making the operation of the system less sensitive to the difierent secondaryemission characteristics of various types.

Briefly the invention in its broadest aspect provides a method for the fabrication of arecording or printing head for electrostatically recording or printing on a recording medium, comprising the following steps: winding suitable wire about an electrically non-conductive rod having at least one fiat side, turns of the wire being spaced from each other; oxidizing the wire winding, covering it with a melted layer of glass frit, and permitting the frit to harden; lapping the frit on the flat side of the rod until windings are exposed through the frit coating; securing to a second electrically non-conductive bar similar to the first, and by means of a thin layer of glass frit, a thin strip of suitable metal properly oxidized to form the strip or bar electrode; bonding the two rods together with the flat sides facing each other and with a thin strip of ribbon glass between the bar electrode and the exposed wire windings, by applying heat and pressure sufiicient to cause the frit on the two rods and the ribbon glass to flow together; and finally after the joined rods have cooled, lapping to remove unwanted parts of the wire winding around the outside of the bars so that an edge of the bar electrode and wirenow pin-ends are exposed on one side and only the opposite wire ends are exposed on the opposite side. The unit as now fabricated comprises a recording head in accordance with the invention, and which in another aspect of the invention, may now be bonded to the faceplate of a cathode-ray tube whereby the exposed pin and bar electrodes on one side are on the outside of the envelope and the exposed ends of the pin electrodes on the opposite side are on the inside of the tube, thus to form the targets for the cathode beam during printing or recording.

The invention will be more fully appreciated from the following description of the preferred embodiment thereof taken in conjunction with the accompanying drawings, wherein:

FIG. 1 is a schematic plan view of a cathode-ray tube incorporating a pin-bar electrostatic recording head in accordance with the invention;

FIG. 2 is a schematic elevational view of the cathoderay tube as seen in FIG. 1, and showing the head in association with a back electrode and a record medium;

FIG. 3 is a perspective view of two electrically insulating rods used in the method of the invention;

FIG. 4 is a view similar to FIG. 3 but showing the two glass rods after steps of the method have been performed on them;

FIG. 5 is a transverse sectional view illustrating the rods in their joined condition prior to the final lapping or grinding step;

FIG. 6 is a fragmentary front elevational view of the finished recording head; and

FIG. 7 is a fragmentary sectional view of the head shown in FIG. 6 as applied to the faceplate of a cathoderay tube, as seen in FIGS. 1 and 2.

Now with the reference to the details of the various figures of the drawings, it will be understood that the method in accordance with the preferred form of the invention comprises the following steps.

Two electrically insulating rods 10 and 12 (FIG. 3) approximately 4" square by 3" long are provided, and may be cut from flat A thick lead-glass sheet, such as manufactured by Corning Glass Works and identified as No. 8870.

In the next step, as seen in FIG. 5, rod 10 has wound upon it, using suitable coil winding equipment, a .004" diameter molybdenum wire 14 in evenly spaced, preferably helical, coils at a pitch of .010", and for approximately 2" along the length of the rod.

Next the wire is oxidized by any suitable means, such as a gas-oxygen flame, after which thermal setting solder glass frit 16 is applied to the rod in an amount sufficient to cover the winding with a layer of the frit. While other frit might be used, that produced by Corning Glass Works and identified as No. 7572 has been found desirable. This step can be accomplished in an oven by the procedure outlined in the Corning Product Information Bulletin authored by L. C. Liptak, November 21, 1957, or by spreading on the rod, as with a thin metal spatula, a thin coating of melted frit after the rod has been heated, and then heating the frit by a hand-held glass blowers gasoxygen torch. The temperature should not be allowed to exceed approximately 550 C. which is the softening point of the lead-glass rod.

After cooling, one surface 18 (FIG. of the so prepared rod is ground or lapped until the windings 20 are just exposed through the frit coating, as indicated by line 22.

The rod 12 is now coated on one side 24 only, with a thin layer of melted glass frit 26, after which a strip 28 of Nichrome approximately .003" thick by wide by 3" long which has been properly oxidized is laid on top of the frit along the length of rod 12 with a small length 30 thereof, as seen in FIGS. 1 and 6, extending out past the end of the rod 12 to be used later for connection purposes. The Nichrome strip 28 is laid off center with one of its edges 32 about 5 from the edge of the rod, and then under heat and moderate pressure to insure flatness, the strip is fused to the frit.

Now as seen in FIG. 5 the two glass rods prepared in accordance with the above steps are placed together with the exposed surface 18 of the windings 20 facing the exposed surface 34 of the N-ichrome strip, and with a strip 36 of .0013" thick capacitor ribbon glass between them. Such ribbon .glass is manufactured by Corning Glass Works as No. 8871. Heat at approximately 550 C. is then applied along with moderate pressure until the frit and the glass strip fuse together thus to join the rods together as a single integral unit.

The integral unit is then cooled and lapped, preferably on all sides, so as to remove all remaining unwanted parts such as the excess wire winding around the outside of bar 10, and the excess glass, all to the extent indicated by the heavy broken lines 38 on FIG. 5 so that, as seen in FIGS. 6 and 7, an edge 40 of the strip 28 and the ends 42 of the remaining wire portions, which we will now callpins 43, are exposed on one side 44 and only the pin ends 46 are exposed on the opposite side 48.

' It is desirable that the length of the pins 43 sealed within the unit should be as short aspossible in the area over which the bar 28 is in close proximity to the pins, thus to minimize the capacity effect between the pins and the bar. Therefore, it is preferred to la-p the unit from the front 44, that is, where both the edge 40 of the bar 28 and pin ends 42 are exposed, until the bar becomes as narrow as possible without weakening the print head structure. Then the inside surface 48 of the unit, or that surface where only pin ends 48 are exposed to the electron beam, is lapped down until the inside edge 50 of the bar is almost exposed, but not quite, since it is essential that only the pins be struck by the beam.

The finished recording head 51 may be approximately .040" to .050 thick and as long as desired, in the present case three inches.

The pin-bar recording unit 51, as described above, can now be sealed onto either a glass faceplate 52 of the cathode-ray tube 54, as indicated at 56 in FIG. 7, or even a metal faceplate such as is common in the industry today. In either case the recording unit is sealed over an opening or window 57, and sealing can be accomplished by the use of well known glass frit techniques.

While the drawings and the above description illustrate the method by which a single pin-bar electrode may be fabricated, it is within the concept and scope of the invention to fabricate a complete matrix by joining a plurality of such units together at the surfaces 58 and 60 in FIG. 6 as indicated by the broken lines 62.

Referring now to FIG. 1 and 2, it is seen that the cathode-ray tube 54 may comprise one of conventional shape having an elongated envelope 64 with a narrow neck portion 66 at one end, and a flared portion 68 at its opposite end across which the faceplate 52 is bonded. The narrow neck portion 66 houses a conventional beam producing gun 70 and deflection plates 72 for directing the beam to select the pins 43. In operation a back electrode 74 (FIG. 2) is provided slightly spaced from the recording unit 51 to provide a gap 76 through which a record medium 78 is threaded.

In any of the steps involving the glass frit, it will be understood that the frit can be applied in a melted form under heat, or the frit may be mixed with a binder, such as collodion, or nitrocellulose in amyl acetate.

What is claimed is:

1. The method of fabrication of a recording head for electrostatically recording on a record medium, comprising the following steps; winding electrically conductive wire about a first electrically non-conductive rod having at least one flat side, covering the wire winding with a layer of electrically insulating material, and permitting it to harden; lapping said material on the flat side of the rod until the windings on that side are plane longitudinally and exposed through the said material; securing to a second electrically non-conductive rod similar to the first and by means of a thin layer of electrically insulating material, a thin strip of electrically conductive metal to form an electrode; bonding the two rods together with the flat sides facing each other and with a thin strip of electrically insulating material between the said electrode and the exposed wire windings by applying heat and pressure suflicient to cause the electrically insulating material on the two rods to flow together, and permitting the joined rods to cool; and lapping the bonded rods to remove unwanted parts of the wire winding around the outside of the rods so that an edge of the said electrode and wire ends are exposed on one side, and only the opposite wire ends are exposed on the opposite side.

2. The method of fabrication of a recording head for electrostatically recording on a record medium, comprising the following steps: winding electrically conductive wire snugly about a first electrically non-conductive rod having at least one flat side, windings of said wire being spaced from each other; oxidizing the wire winding; covering the wire winding with a layer of glass frit and permitting the frit to harden; lapping the frit on the flat side of the rod until the windings on that side are plane longitudinally and exposed through the frit; securing to a second electrically non-conductive rod similar to the first and by means of a thin layer of glass frit, a thin strip of electrically conductive metal properly oxidized to form a bar electrode; bonding the two rods together with the flat sides facing each other and with a thin strip of ribbon glass between the bar electrode and the exposed wire windings by applying heat and pressure sufficient to cause the frit on the two rods and the ribbon glass to flow together, and permitting the joined rods to cool; and lapping the bonded rods to remove unwanted parts of the wire winding around the outside of the rods so that an edge of the bar electrode and wire ends are exposed on one side, and only the opposite wire ends are exposed on the opposite side.

3. The method of fabrication of a pin-bar recording or printing head for electrostatically recording or printing on a record medium, comprising the following steps: winding electrically conductive wire about a first elongated electrically non-conductive rod of rectangular cross-section, the turns of wire being evenly spaced from each other; oxidizing the Wire winding; covering the wire winding with a melted layer of glass hit and permitting the frit to harden; lapping the frit on one side of the wire until the windings on that side are plane longitudinally and exposed through the frit; securing to one side of a second electrically non-conductive rod similar to the first by means of a thin layer of glass frit, a thin strip of electrically conductive metal properly oxidized to form the bar electrode; bonding the two rods together as a unit with the said one sides facing each other and with a thin strip of ribbon glass between the bar electrode and the exposed wire windings by applying heat and pressure sufficient to cause the frit on the two rods and the ribbon glass to fiow together, and permitting the joined rods to cool; and grinding and lapping the bonded rods to remove unwanted parts of the rods and the wire winding around the outside of the rods so that only an edge of the bar electrode and wire ends are exposed on one side of the unit, and only the opposite wire ends are exposed on the opposite side thereof.

4. The method of fabrication of a pin-bar recording or printing head for electrostatically recording or printing on a record medium comprising the following steps: winding suitable wire in helical turns about a first elongated electrically non-conductive rod of rectangular crosssection, the turns of wire being evenly spaced from each other; oxidizing the wire winding; covering the wire winding with a melted layer of glass frit and permitting the frit to harden; lapping the frit on one side of the rod until the windings on that side are plane longitudinally and exposed through the frit; securing to one side of a second electrically non-conductive rod similar to the first by means of a thin layer of glass frit, an elongated thin strip of suitable oxidized metal to form the bar electrode with a portion extending beyond one end of the rod for connection purposes; bonding the two rods together as a unit with the said one sides facing each other and with a thin strip of ribbon glass between the bar electrode and the exposed wire windings by applying heat and pressure sufficient to cause the frit on the two rods and the ribbon glass to flow together and permitting the joined rods to cool; and grinding and lapping the bonding unit to remove unwanted parts thereof and of the wire winding around the outside of the unit so that only an edge of the electrode and wire ends are exposed on one side of the .unit, and only the opposite wire ends are exposed on the opposite side thereof.

5. The method of fabrication of a combined cathode ray pin-bar recording or printing head for electrostatically recording or printing on a record medium, comprising the following steps: winding electrically conductive wire about a first electrically non-conductive rod having at least one fiat side, the turns of Wire being spaced from each other;

covering the wire Winding with a layer of electrically insulating material and permitting it to harden; lapping the said material on the flat side of the rod until windings on that side are exposed through the said material; securing to a second electrically non-conductive rod similar to the first by means of a thin layer of electrically insulating material, a thin strip of electrically conductive metal to form the bar electrode; bonding the two rods together as a unit with the flat sides facing each other and with a thin strip of electrically insulating material between the bar electrode and the exposed wire windings by applying heat and pressure suificient to cause the electrically insulating material to flow together and permitting the joined rods to cool; lapping and grinding the bonded rods to remove unwanted parts of the rods and of the wire winding around the outside of the bars so that only an edge of the bar electrode and wire ends are exposed on one side, and only the opposite wire ends are exposed on the opposite side, thus to form a head unit with a plurality of pin electrodes and a bar electrode; bonding the so constructed head unit to the envelope of a cathode ray tube in a manner whereby the exposed pin and bar electrodes on one side of the head unit are on the outside of the envelope, and the exposed ends of the pin electrodes on the opposite side of the head unit are on the inside of the envelope thus to form the targets of the cathode beam during printing or recording.

6. The method of fabrication of a combined cathode ray pin-bar recording or printing ead for electrostatically recording or printing on a record medium comprising the following steps: winding electrically conductive wire snugly in helical turns about an elongated electrically non-conductive rod of rectangular cross-section, the turns of wire being evenly spaced from each other and oxidizing the wire winding; covering the wire winding with a melted layer of glass frit; permitting the frit to harden; lapping the frit on one side of the wire until the windings on that side are exposed through the frit coating; securing to one side of a second electrically non-conductive rod similar to the first by means of a thin layer of glass frit, a thin strip of suitable metal properly oxidized to form the bar electrode; bonding the two rods together as a unit with the said one sides of the two rods facing each other and with a thin strip of ribbon glass between the bar electrode and the exposed wire windings by applying heat and pressure sufiicient to cause the frit on the two rods and the ribbon glass to flow together and permitting the joined rods to cool; grinding and lapping the unit to remove unwanted parts of the rods and of the wire winding around the outside of the bars so that only an edge of the bar electrode and wire ends are exposed on one side, and only the opposite wire ends are exposed on the opposite side, thus to form a heat unit with a plurality of pin electrodes and a bar electrode; and bonding the so constructed head unit to and over a window in the face-plate of a cathode ray tube in a manner whereby the exposed pin and bar electrodes on one side of the head unit are on the outside of the face-plate, and the exposed ends of the pin electrodes on the opposite side of the head unit are on the inside of the face-plate thus to form the targets of the cathode beam during printing or recording.

References Cited in the file of this patent UNITED 'STATES PATENTS 2,825,184 Charlotte Mar. 4, 1958 

5. THE METHOD OF FABRICATION OF A COMBINED CATHODE RAY PIN-BAR RECORDING OR PRINTING HEAD FOR ELECTROSTATICALLY RECORDING OR PRINTING ON A RECORD MEDIUM, COMPRISING THE FOLLOWING STEPS: WINDING ELECTRICALLY CONDUCTIVE WIRE ABOUT A FIRST ELECTRICALLY NON-CONDUCTIVE ROD HAVING AT LEAST ONE FLAT SIDE, THE TURNS OF WIRE BEING SPACED FROM EACH OTHER; COVERING THE WIRE WINDING WITH A LAYER OF ELECTRICALLY INSULATING MATERIAL AND PERMITTING IT TO HARDEN; LAPPING THE SAID MATERIAL ON THE FLAT SIDE OF THE ROD UNTIL WINDINGS ON THAT SIDE ARE EXPOSED THROUGH THE SAID MATERIAL; SECURING TO A SECOND ELECTRICALLY NON-CONDUCTIVE ROD SIMILAR TO THE FIRST BY MEANS OF A THIN LAYER OF ELECTRICALLY INSULATING MATERIAL, A THIN STRIP OF ELECTRICALLY CONDUCTIVE METAL TO FORM THE BAR ELECTRODE; BONDING THE TWO RODS TOGETHER AS A UNIT WITH THE FLAT SIDES FACING EACH OTHER AND WITH A THIN STRIP OF ELECTRICALLY INSULATING MATERIAL BETWEEN THE BAR ELECTRODE AND THE EXPOSED WIRE WINDINGS BY APPLYING HEAT AND PRESSURE SUFFICIENT TO CAUSE THE ELECTRICALLY INSULATING MATERIAL TO FLOW TOGETHER AND PERMITTING THE JOINED RODS TO COOL; LAPPING AND GRINDING THE BONDED RODS TO REMOVE UNWANTED PARTS OF THE RODS AND OF THE WIRE WINDING AROUND THE OUTSIDE OF THE BARS SO THAT ONLY 